Attendance Report in MySql

I want to write a query to generate attendance report of employee. First I will tell you how the presence of employee is stored in my database.

I have following tables.

Employee Table with Columns

    emp_id  emp_Name   Joining_Date
     1      john         11-01-2012
     2      Scott        12-01-2012


Holiday Table

Holiday_Name         Date 
Chrismas          25-12-2012  
Dushera           08-03-2012
Independance Day  15-08-2012

Leave Table

Subject  from_Date     to_Date      Emp_Id     status 
PL       02-01-2012    04-01-2012      1       Approved
CL       11-01-2012    12-01-2012      2       Declined      


Doctor Table

Subject   Call_Date    call_Done_By(emp_id)
 Call     15-01-2012      1
 CA       21-02-2012      2

Chemist Table
Subject   Call_Date    call_Done_By(emp_id)
Chemist   1-02-2012     2
Texo      21-03-2012    1

If employee is visited to doctor or chemist,that particular date is stored in that particular doctor or chemist table with employee_id

Now person will select year and month and he should be able to get attendance report in following format Example : suppose user selects year as '2011' and month as 'Dec' then output should be

Employee   year  Month    1  2   3   4   5   6    7.... 
 John      2011   Nov     Y  Y   Y   Y   Y   L    S....
 Scott     2011   Nov     Y  Y   L   M   Y   L    S

here in output 1,2,3.... are days from 0-30 for a month which we can write using 'case'

Consider if employee is present on day show its status as 'Y' else L else if he gone to any customer like doctor,chemist,then replace it with 'S'.

So how should I write a query to achieve this output?? any suggestions will be helpful for me....

Here is a long way that should work as expected:

SELECT
    Employee.emp_Name,
    '2011' AS `Year`,
    'Dec' AS `Month`,
    CASE (
        IF(
            DATE('1-12-2011') < DATE(Employee.Joining_Date)),
            '0' --Not joined yet
            IF (
                (SELECT COUNT(*) FROM Holiday WHERE DATE('1-12-2011') = DATE(Holiday.date)) = 1,
                '1', --National Holiday
                IF (
                    (SELECT COUNT(*) FROM Leave WHERE DATE('1-12-2011') > DATE(Leave.to_Date) AND DATE('1-12-2011') < DATE(Leave.from_Date) AND Leave.Emp_Id = Employee.emp_id) = 1,
                    '2', --On Leave
                    IF(
                        (SELECT COUNT(*) FROM Doctor WHERE DATE('1-12-2011') > DATE(Doctor.Call_Date) AND Doctor.call_Done_By = Employee.emp_id) = 1 OR 
                        (SELECT COUNT(*) FROM Chemist WHERE DATE('1-12-2011') > DATE(Chemist.Call_Date) AND Chemist.call_Done_By = Employee.emp_id) = 1,
                        '3' --Visit Doctor or Chemist
                        '4' --Employee was at work
                    )
                )
            )
        )
    )
        WHEN 0 THEN 'N/A' --Not joined yet
        WHEN 1 THEN 'L' --National Holiday
        WHEN 2 THEN 'L' --On Leave
        WHEN 3 THEN 'S' --Visit Doctor or Chemist
        ELSE 'Y' --Employee was at work
    END AS `1`, --first day of month
    ... AS `2`, --repeat for second day of the month till max day of current month replace '1-12-2011' with each different day of month
    ...
    ... AS `30`
FROM
    Employee

My suggestion is to create a view that does the if statement for each employee that way your code will be easier to maintain. Please keep in mind that this is pseudo code that might need some some changing to run.

Hope this helps.